Photocurable/therosetting resin composition, photosensitive dry film formed therefrom and method of forming pattern with the same

ABSTRACT

A photocurable and thermosetting resin composition comprising (A) a photosensitive prepolymer having a carboxyl group in combination with at least two ethylenically unsaturated double bonds in its molecule, (B) a polymerization initiator, (C) a diluent, (D) an oxetane compound having at least two oxetanyl groups in its molecule, and (E) a curing promotor is developable with an alkaline solution and can be formulated as a one package preparation. Such a photocurable and thermosetting resin composition and a photosensitive dry film prepared by the use thereof are useful as various resist materials and electrical insulating materials, particularly as solder resists for printed circuit boards, interlaminar insulating materials for build-up multi-layer printed circuit boards, and the like.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. application Ser. No.10/256,009, filed Sep. 27, 2002 now U.S. Pat. No. 6,844,130, which is acontinuation of Application PCT/JP01/02590, filed Mar. 28, 2001, nowabandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a photocurable and thermosetting resincomposition and a photosensitive dry film formed from the composition,and more particularly relates to a photocurable and thermosetting resincomposition which is suitable for the formation of a solder resist etc.in a household grade printed circuit board and an industrial gradeprinted circuit board and a photosensitive dry film which is suitablefor various applications such as the production of circuit boards andthe mounting of the electronic parts. This invention relates further toa method for forming a pattern by the use of the photocurable andthermosetting resin composition and the photosensitive dry filmmentioned above.

2. Description of the Prior Art

In the household grade printed circuit boards and the industrial gradeprinted circuit boards, generally a solder resist is formed beforesupplying a solder during the step of mounting electronic parts for thepurpose of preventing molten solder from adhering to irrelevant portionsand protecting circuits. As a resin composition for this solder resist,a developing type solder resist composition which is used to form apattern by a photolithographic method is widely adopted from theviewpoint of ensuring highly accurate formation of circuits with highdensity. Particularly, with due respect to the problem of environmentalsafety and from the viewpoint of cost, the solder resist composition ofthe alkali developing type which implements development with a diluteaqueous alkaline solution has come to play the leading role.

Such a solder resist composition usually contains a polyfunctional epoxycompound having two or more epoxy groups as a thermosetting componentfor the purpose of improving the resistance to soldering heat. However,since the polyfunctional epoxy compound exhibits high reactivity, thephotocurable and thermosetting resin composition containing thiscompound exhibits unduly short shelf life (useful life) and is liable togain in viscosity prior to being applied to a blank circuit board. As aresult, it is possible to formulate it as the one-package type only withdifficulty. Accordingly, the composition requires to be formulated asthe two-package type consisting of a hardener solution containing apolyfunctional epoxy compound as a main component thereof and a mainagent solution containing a photosensitive prepolymer as a maincomponent thereof and a curing promotor etc. added thereto. This posesthe problem in working properties because it is necessary to mix themimmediately prior to use.

Further, when the photocurable and thermosetting resin compositioncontaining the polyfunctional epoxy compound is formed into a dry film,the shelf life (useful life) of this film becomes short and thepreservation in the refrigerated state at a temperature of not more than0° C. is required. That is to say, it is deficient in shelf stability atroom temperature. Further, this dry film poses the problem in workingproperties because increase of its temperature to room temperature isrequired prior to use thereof.

When the photocurable and thermosetting resin composition containing thepolyfunctional epoxy compound is applied to a substrate, exposed tolight, developed and then thermally cured, a cured film having excellentproperties such as hardness owing to the cross-linking reaction of thepolyfunctional epoxy compounds is obtained. However, when thecross-linking reaction unduly proceeds, there is the possibility ofcausing shrinkage of the coating film on curing and cracks therein.

SUMMARY OF THE INVENTION

An object of the present invention, therefore, is to provide an alkalideveloping type photocurable and thermosetting resin composition, whichis free from such defects as mentioned above, has no possibility ofcausing shrinkage on curing during the step of thermal curing, iscapable of producing a cured film excelling in various properties suchas resistance to heat, fastness of adhesion, and electrical insulatingproperties, thereby capable of improving the insulating reliability,excels in storage stability and thus is capable of being formulated as aone-package preparation.

Another object of the present invention is to provide a photosensitivedry film consisting of an alkali developing type photocurable andthermosetting resin composition, which is capable of producing a curedfilm excelling in various properties such as resistance to heat,fastness of adhesion, and electrical insulating properties, and allowspreservation at room temperature.

Further objects of the present invention are to provide a method offorming a pattern by the use of the photocurable and thermosetting resincomposition or the photosensitive dry film as mentioned above and toprovide a printed circuit board having a solder resist pattern formed bythe method.

To accomplish the objects mentioned above, the first aspect of thepresent invention consists in providing a photocurable and thermosettingresin composition characterized by comprising (A) a photosensitiveprepolymer having a carboxyl group in combination with at least twoethylenically unsaturated double bonds in its molecule, (B) apolymerization initiator, (C) a diluent, (D) an oxetane compound havingat least two oxetanyl groups in its molecule, and (E) a curing promotor.

Since the photocurable and thermosetting resin composition mentionedabove contains as a thermosetting component a polyfunctional oxetanecompound (D) having oxetanyl groups of a four membered ring which reactwith the carboxyl groups of the photosensitive prepolymer (A) during thestep of thermal curing to cause primary hydroxyl groups preponderantly,the resultant cured film is excellent in adhesiveness to a substrate ascompared with that obtained by the composition using an epoxy compoundwhich causes secondary hydroxyl groups preponderantly by the reactionwith the above prepolymer. Further, since the cured film contains alarge number of ethylene units after the reaction because of the fourmembered ring, it scarcely suffers volume shrinkage and excels intoughness. As a result, there is obtained a cured film which exhibitsexcellent resistance to cracking. Furthermore, since the reactivity ofthe polyfunctional oxetane compound is lower than that of thepolyfunctional epoxy compound, the photocurable and thermosetting resincomposition containing the polyfunctional oxetane compound exhibitslonger shelf life (useful life), can be formulated as a one packagepreparation, and allows formation of a photosensitive dry film excellingin shelf stability at room temperature, which provides variousadvantages in terms of workability.

In accordance with the second aspect of the present invention, there isprovided a photosensitive dry film characterized by comprising asupporting film and at least a dry film layer of the aforementionedphotocurable and thermosetting resin composition formed thereon. In apreferred embodiment, a protective film is further laminated on the dryfilm layer mentioned above.

The photosensitive dry film mentioned above excels in formation of finepatterns and further in various properties such as storage stability,developing properties, resistance to cracking (toughness), fastness ofadhesion, and hardness.

The third aspect of the present invention consists in providing a methodof forming a pattern. One embodiment thereof is characterized bycomprising the steps of tightly superposing the photosensitive dry filmmentioned above on a substrate on which a pattern is formed in such amanner that the dry film layer is brought into contact with thesubstrate, separating the supporting film from the dry film layer, thenexposing the layer to light through a patterned mask, and effectingdevelopment to remove an unexposed area of the layer. In the case of thephotosensitive dry film further containing a protective film laminatedon the dry film layer mentioned above, after separating the protectivefilm from the photosensitive dry film, the photosensitive dry film istightly superposed on a substrate on which a pattern is formed in such amanner that the dry film layer is brought into contact with thesubstrate as mentioned above, the supporting film is separated from thedry film layer and then this layer is exposed to light and developed inthe same manner as mentioned above. When the photocurable andthermosetting resin composition is used, it is applied to a substrate onwhich a pattern is formed, dried, thereafter exposed to light through apatterned mask, and then subjected to development to remove theunexposed area of the layer. By such methods, it is possible to form aprescribed resin insulating pattern such as a solder resist pattern withgood workability.

In accordance with the fourth aspect of the present invention, there isprovided a printed circuit board having a solder resist pattern formedthereon in the manner as mentioned above.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors, after continuing a diligent study in search of amethod for solving the problems mentioned above, have made the findingsthat the photocurable and thermosetting resin composition obtained byusing a polyfunctional oxetane compound as a thermosetting component incombination with a photosensitive prepolymer having a carboxyl grouptogether with at least two ethylenically unsaturated double bonds in itsmolecule is developable with an aqueous alkaline solution and, at thesame time, can be formulated as a one-package preparation, and that whenthe coating film of the composition is thermally cured after exposure tolight and development, there is obtained a cured film excelling invarious properties such as resistance to heat, fastness of adhesion, andelectrical insulating properties, without causing any shrinkage oncuring. The present inventor shave further found that the photocurableand thermosetting resin composition mentioned above allows formation ofa photosensitive dry film which can be stored at room temperature and isexcellent in shelf life (useful life), and that when the dry film layer(photosensitive layer) of this photosensitive dry film is transferredonto a substrate and thermally cured after exposure to light anddevelopment, there is obtained a cured film excelling in variousproperties such as resistance to heat, fastness of adhesion, andelectrical insulating properties, without causing any shrinkage oncuring as mentioned above.

Specifically, since the photocurable and thermosetting resin compositionof the present invention contains as a thermosetting component anoxetane compound (D) having oxetanyl groups of a four membered ringwhich react with the carboxyl groups of the photosensitive prepolymer(A) during the step of thermal curing to cause primary hydroxyl groupspreponderantly, the resultant cured film is excellent in adhesiveness toa substrate as compared with that obtained by the composition using anepoxy compound which causes secondary hydroxyl groups preponderantly bythe reaction with the above prepolymer. Further, since the cured filmcontains a large number of ethylene units after the reaction because ofthe four membered ring, it scarcely suffers volume shrinkage and excelsin toughness. As a result, there is obtained a cured film which exhibitsexcellent resistance to cracking. Furthermore, since the reactivity ofthe polyfunctional oxetane compound is lower than that of thepolyfunctional epoxy compound, the photocurable and thermosetting resincomposition containing the polyfunctional oxetane compound exhibitslonger shelf life (useful life), can be formulated as a one packagepreparation, and allows formation of a photosensitive dry film excellingin shelf stability at room temperature. The use of such a photocurableand thermosetting resin composition or photosensitive dry film isadvantageous in terms of workability. Moreover, another effect offurther improving the insulating reliability may also be attaineddepending on the method for the production of the oxetane compound.

Now, the present invention will be described in detail below. First, asthe component (A) mentioned above, any of photosensitive prepolymers(oligomers or polymers) having a carboxyl group in combination with atleast two ethylenically unsaturated bonds in its molecule may be usedand not limited to particular prepolymers. However, the photosensitiveprepolymers as listed below can be particularly advantageously used:

(1) products obtained by the esterification (complete esterification orpartial esterification, preferably complete esterification) of an epoxygroup of (a) a polyfunctional epoxy compound having at least two epoxygroups in its molecule with a carboxyl group of (b) an unsaturatedmonocarboxylic acid and the subsequent reaction of (c) a saturated orunsaturated polybasic acid anhydride with the resultant hydroxyl group,

(2) products obtained by the reaction of (meth)acrylic acid with acopolymer composed of an alkyl (meth)acrylate and a glycidyl(meth)acrylate and the subsequent reaction of a saturated or unsaturatedpolybasic acid anhydride (c) with the resultant reaction product,

(3) products obtained by the reaction of (meth)acrylic acid with acopolymer composed of a hydroxyalkyl (meth)acrylate, an alkyl(meth)acrylate, and a glycidyl (meth)acrylate and the subsequentreaction of a saturated or unsaturated polybasic acid anhydride (c) withthe resultant product,

(4) products obtained by the partial reaction of a glycidyl(meth)acrylate with a copolymer composed of an alkyl (meth)acrylate and(meth)acrylic acid,

(5) products obtained by causing a saturated or unsaturated polybasicacid anhydride (c) to react with a reaction product (I) of apolyfunctional epoxy compound (a) having at least two epoxy groups inits molecule, an unsaturated monocarboxylic acid (b), and a compound (d)having at least two hydroxyl groups and one other reactive group otherthan a hydroxyl group capable of reacting with an epoxy group in itsmolecule,

(6) products obtained by causing a hydroxyalkyl (meth)acrylate to reactwith a copolymer of such an unsaturated polybasic acid anhydride asmaleic anhydride with an aromatic hydrocarbon having a vinyl group suchas styrene, and

(7) unsaturated group-containing polyurethane carboxylate resins such asproducts obtained by reacting the reaction product (I) mentioned abovewith a saturated or unsaturated polybasic acid anhydride (c) and anunsaturated group-containing monoisocyanate (e).

The term “(meth)acrylic acid” as used in this specification meansacrylic acid, methacrylic acid, or a mixture thereof and the term“(meth)acrylate” means acrylate, methacrylate, or a mixture thereof.

Since the photosensitive prepolymer (A) mentioned above has numerousfree carboxyl groups added to the side chain of a backbone polymer, thecomposition containing this photosensitive prepolymer is developablewith a dilute aqueous alkaline solution. When the applied coating filmof the composition is developed after exposure to light and then postcured, the addition reaction of the oxetanyl groups of an oxetanecompound (D) separately added to the composition as a thermosettingcomponent with the free carboxyl groups in the side chain of thephotosensitive prepolymer takes place and the coating film is convertedinto a film excelling in such properties as resistance to heat,resistance to solvent, resistance to acid, adhesiveness, resistance toelectroless gold plating, electrical properties, and hardness. The acidvalue of the photosensitive prepolymer (A) mentioned above, thoughhaving an appropriate range thereof varied with the kind of prepolymer,should fall in the range of 30 to 160 mg KOH/g, preferably in the rangeof 40 to 120 mg KOH/g. Any deviation of the acid value from theaforementioned range is undesirable because the resin will manifestinsufficient solubility in an aqueous alkaline solution if the acidvalue is less than 30 mg KOH/g. Conversely, the acid value exceeding 160mg KOH/g will give cause to deteriorate the various properties of thecured film such as resistance to alkalis and electrical propertiesexpected of a resist.

The resin (1) mentioned above is obtained by causing the product of thereaction of such a polyfunctional epoxy compound as will be specificallydescribed hereinafter with an unsaturated monocarboxylic acid to reactwith such a dibasic acid anhydride as phthalic anhydride or such anaromatic polycarboxylic anhydride as trimellitic anhydride orpyromellitic anhydride. In this case, the resin obtained by the reactionof about 0.15 mol or more of a polybacic acid anhydride with each of thehydroxyl groups possessed by the reaction product of the polyfunctionalepoxy compound with an unsaturated monocarboxylic acid proves to besuitable. When the number of ethylenically unsaturated bonds present inone molecule of the resin is small, the produced composition has a lowspeed of photo-curing. It is therefore desired to use a novolak typeepoxy compound as the raw material. A bisphenol A type epoxy resin maybe used in combination therewith for the purpose of lowering theviscosity of the composition.

The copolymers which are base polymers of the resins (2) and (3)mentioned above are obtained by using as monomers such alkyl(meth)acrylates and glycidyl (meth)acrylates or further hydroxyalkyl(meth)acrylates as mentioned above and copolymerizing these monomers byany of the well-known methods such as, for example, the method ofsolution polymerization. The alkyl (meth)acrylates mentioned above arealkyl esters of acrylic acid or methacrylic acid. The alkyl group of thealkyl esters is an aliphatic hydrocarbon group having 1 to 6 carbonatoms. As alkyl (meth)acrylates, esters of acrylic acid or methacrylicacid with methyl, ethyl, propyl, isopropyl, butyl, hexyl, etc. may becited. It should be noted, however, that these are not exclusiveexamples.

The hydroxyalkyl (meth)acrylates mentioned above are hydroxyalkyl estersof acrylic acid or methacrylic acid. The hydroxyalkyl group of thesehydroxyalkyl esters is desired to be an aliphatic hydrocarbon grouphaving 1 to 6 carbon atoms and containing a primary hydroxyl group. Thereason for this desirability is that it is desirable to select and use ahydroxyalkyl (meth)acrylate containing a primary hydroxyl group as oneof the component monomers of the aforementioned copolymer from theviewpoint of the ease with which the product of the reaction of thecopolymer with (meth)acrylic acid is caused to react further with apolybasic acid anhydride. As typical examples of such hydroxyalkyl(meth)acrylates containing a primary hydroxyl group, 2-hydoxyethylacrylate, 2-hydroxyethyl methacrylate, etc. may be cited. It should benoted, however, that these are not exclusive examples.

In the copolymer as the basis of the resin (2) mentioned above, themolar ratio of an alkyl (meth)acrylate to glycidyl (meth)acrylate isdesired to be in the approximate range of 40:60 to 80:20. On the otherhand, in the copolymer as the basis of the resin (3) mentioned above,the molar ratio of a hydroxyalkyl (meth)acrylate to an alkyl(meth)acrylate to glycidyl (meth)acrylate is desired to be in theapproximate range of 10–50:10–70:20–60, preferably in the range of15–30:30–50:30–50. If the proportion of glycidyl (meth)acrylate to thecopolymer is unduly low from the lower limit of the range mentionedabove, the copolymer will be at a disadvantage in acquiring an undulylow photo-curing properties. Conversely, if this proportion exceeds theupper limit of the range mentioned above, the copolymer will be at adisadvantage in failing to allow the reaction of synthesis of aphotosensitive resin to proceed smoothly.

In the resins (2) to (4) mentioned above, the degree of polymerizationof the copolymer obtained by copolymerizing the component monomers, asexpressed by weight-average molecular weight, is desired to be in theapproximate range of 5,000 to 70,000, preferably in the range of 10,000to 60,000. If the weight-average molecular weight is less than 5,000,the coating film containing the resin will be at a disadvantage inacquiring unduly low dryness to the touch of finger. Conversely, if itexceeds 70,000, the coating film will be at a disadvantage in acquiringan unduly low developing property. Further, such vinyl compounds asstyrene and methylstyrene may be used in a proportion not so large as toadversely affect the characteristic properties of the composition inaddition to the component monomers mentioned above.

The reaction for the synthesis of the resin (5) mentioned above isattained by the first method which comprises causing an unsaturatedmonocarboxylic acid (b) [or a compound (d)] to react with apolyfunctional epoxy compound (a) and then causing a compound (d) [or anunsaturated monocarboxylic acid (b)] to react with the resultantreaction product or by the second method which comprises causingsimultaneous reaction of a polyfunctional epoxy compound (a), anunsaturated monocarboxylic acid (b), and a compound (d). Though thesetwo methods are both available, the second method proves moreadvantageous.

Appropriately, the reaction mentioned above is accomplished between oneequivalent weight of the epoxy group of the polyfunctional epoxycompound (a) and a total of about 0.8 to 1.3 mols, more preferably about0.9 to 1.1 mols, of the unsaturated monocarboxylic acid (b) and thecompound (d). Properly, the ratio of the amounts of the unsaturatedmonocarboxylic acid (b) and the compound (d) to be used is such that theamount of the compound (d) to be used may fall in the approximate rangeof 0.05 to 0.5 mol, more preferably 0.1 to 0.3 mol, based on 1 mol ofthe total of the amounts of the unsaturated monocarboxylic acid (b) andthe compound (d).

In the reaction for the synthesis of the resin(5) mentioned above, it isappropriate to use a diluent, for example, such organic solvents as willbe cited hereinbelow and such reactive monomers as carbitol(meth)acrylate, phenoxyethyl (meth)acrylate, pentaerythritoltetra(meth)acrylate, trimethylolpropane tri(meth)acrylate,tris(hydroxyethyl) isocyanurate tri(meth)acrylate, and dipentaerythritolhexa(meth)acrylate. Further, for promoting the reaction, it isappropriate to use a catalyst such as, for example, triethyl amine,benzyl dimethyl amine, methyl triethyl ammonium chloride, benzyltrimethyl ammonium bromide, benzyl trimethyl ammonium iodide, triphenylphosphine, triphenyl stibine, chromium octanoate, and zirconiumoctanoate. Appropriately, the amount of the catalyst to be used is inthe approximate range of 0.1 to 10% by weight, based on the total amountof the mixture of reactants. For preventing the reaction from entrainingpolymerization, it is proper to use a polymerization inhibitor such as,for example, hydroquinone, methyl hydroquinone, hydroquinone monomethylether, catechol, and pyrogallol. The amount of the polymerizationinhibitor to be used appropriately is in the approximate range of 0.01to 1% by weight, based on the amount of the mixture of reactants.Properly, the reaction temperature is in the approximate range of 60 to150° C. and the reaction time in the approximate range of 5 to 60 hours.Thus, the reaction product (I) can be obtained.

Next, the reaction of the reaction product (I) mentioned above and thepolybasic acid anhydride (c) is appropriately carried out between oneequivalent weight of the hydroxyl group in the reaction product (I) andabout 0.1 to 0.9 equivalent weight of the polybasic acid anhydride (c).Appropriately, the reaction temperature is in the approximate range of60 to 150° C. and the reaction time in the approximate range of 1 to 10hours.

The synthesis reaction of the unsaturated group-containing polyurethanecarboxylate resin (7) mentioned above is appropriately effected bycausing the reaction product (I) mentioned above to react with thepolybasic acid anhydride (c) and then causing the unsaturatedgroup-containing monoisocyanate (e) to react with the resultant reactionproduct. The reaction of the reaction product (I) with the polybasicacid anhydride (c) can be effected as described above. Appropriately,this reaction is followed by the reaction between one equivalent weightof the hydroxyl group in the unsaturated group-containing polycarboxylicacid resin resulting from the reaction of the reaction product (I) withthe polybasic acid anhydride (c) and about 0.05 to 0.5 equivalent weightof the unsaturated group-containing monoisocyanate (e). The reactiontemperature appropriately is in the approximate range of 60 to 100° C.Properly this reaction proceeds in the presence of a small amount of acatalyst (such as, for example, dibutyl tin laurate). The preferredreaction time is in the approximate range of 5 to 15 hours.

As concrete examples of the epoxy compound (a) having at least two epoxygroups in its molecule and used for the syntheses of the resins (1),(5), and (7) mentioned above, for example, novolak type epoxy resins(such as, for example, those which are obtained by causing such phenolsas phenol, cresol, halogenated phenols, and alkyl phenols to react withformaldehyde in the presence of an acidic catalyst and then causing theresultant novolaks to react with epichlorohydrin and/or methylepichlorohydrin and which include such commercially available substancesas EOCN-103, EOCN-104S, EOCN-1020, EOCN-1027, EPPN-201, and BREN-Sproduced by Nippon Kayaku Co., Ltd., DEN-431 and DEN-439 produced by TheDow Chemical Company, N-730, N-770, N-865, N-665, N-673, N-695, andVH-4150 produced by Dainippon Ink and Chemicals, Inc.), bisphenol typeepoxy resins (such as, for example, those which are obtained by causingsuch bisphenols as bisphenol A, bisphenol F, bisphenol S, andtetrabromobisphenol A to react with epichlorohydrin and/or methylepichlorohydrin or by causing epichlorohydrin and/or methylepichlorohydrin to react with condensates of diglycidyl ether ofbisphenol A with the bisphenols mentioned above and which include suchcommercially available substances as EPIKOTE 1004 and EPIKOTE 1002produced by Japan Epoxy Resin K.K. and DER-330 and DER-337 produced byThe Dow Chemical Company), trisphenol methane type epoxy resins (suchas, for example, those which are obtained by causing trisphenol methaneor triscresol methane to react with epichlorohydrin and/or methylepichlorohydrin and which include such commercially available substancesas EPPN-501 and EPPN-502 produced by Nippon Kayaku Co., Ltd.),tris(2,3-epoxypropyl) isocyanurate, biphenyl diglycidyl ether, alicyclicor amino group-containing epoxy resins (such as, for example, Celloxide2021 produced by Daicel Chemical Industries, Ltd., Epomic VG-3101produced by Mitsui Petrochemical Industries, Ltd., E-1031S produced byJapan Epoxy Resin K.K., TETRAD-X and TETRAD-C produced by Mitsubishi GasKagaku K.K., and EPB-13 and EPB-27 produced by Nippon Soda Co., Ltd.),copolymer type epoxy resins (such as, for example, copolymer of glycidylmethacrylate with styrene and copolymers of glycidyl methacrylate withstyrene and methyl methacrylate, which include CP-50M and CP-50Sproduced by Nippon Oils & Fats Co., Ltd., and copolymers of glycidylmethacrylate with cyclohexyl maleimide), cardo type epoxy resins (forexample, such a commercially available product as ESF-300 produced byShin-Nittetsu Kagaku K.K.), calixarene type epoxy resins, and otherepoxy resins having special structures may be cited. Among other epoxyresins mentioned above, cresol novolak type epoxy resins, phenol novolaktype epoxy resins, and cardo type epoxy resins having a fluoreneskeleton, etc. prove to be particularly advantageous.

As concrete examples of the unsaturated monocarboxylic acids (b) usedfor the synthesis of the aforementioned resins (1) (5), and (7), forexample, acrylic acid, dimer of acrylic acid, methacrylic acid,β-styrylacrylic acid, β-furfuryl acrylic acid, crotonic acid,α-cyanocinnamic acid, cinnamic acid; half esters obtained by thereaction of a saturated or unsaturated dibasic acid anhydride with a(meth)acrylate having one hydroxyl group per molecule or by the reactionof a saturated or unsaturated dibasic acid anhydride with an unsaturatedmonoglycidyl compound, such as, for example, half esters obtained bycausing a saturated or unsaturated dibasic acid anhydride such assuccinic anhydride, maleic anhydride, phthalic anhydride,tetrahydrophtalic anhydride, hexahydrophthalic anhydride,methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride,itaconic anhydride, and methylendomethylene tetrahydrophthalicanhydride, to react in an equimolar ratio with a (meth)acrylate havingone hydroxyl group per molecule such as hydroxyethyl (meth)acrylate,hydroxypropyl (meth)acrylate, hydroxybutyl (meth)-acrylate, polyethyleneglycol mono(meth)acrylate, glycerin di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acryalte,dipentaerythritol penta(meth)acrylate, and (meth)acrylate of phenylglycidyl ether and half esters obtained by causing a saturated orunsaturated dibasic acid (such as, for example, succinic acid, maleicacid, adipic acid, phthalic acid, tetrahydrophthalic acid, itaconicacid, and fumaric acid) to react in an equimolar ratio with anunsaturated monoglycidyl compound (such as, for example, glycidyl(meth)acrylate and the compounds represented by the following formulae(1) to (4) may be cited. These unsaturated monocarboxylic acids may beused either singly or in the form of a combination of two or moremembers. Among other monocarboxylic acids cited above, acrylic acid andmethacrylic acid, particularly acrylic acid, prove to be particularlydesirable from the viewpoint of the photo-curing properties.

wherein, R¹, R², and R⁵ independently represent a hydrogen atom or amethyl group, R³ represents an aliphatic hydrocarbon of 1 to 12 carbonatoms, and R⁴ represents

As typical examples of the saturated or unsaturated polybasic acidanhydrides (c) used for the synthesis of the aforementioned resins (1)to (3) and (5) to (7), dibasic acid anhydrides such as maleic anhydride,succinic, anhydride, itaconic anhydride, phthalic anhydride,tetrahydrophthalic anhydride, hexahydrophthalic anhydride,methylhexahydrophthalic anhydride, endomethylenetetrahydrophthalicanhydride, methylendomethylenetetrahydrophthalic anhydride, chlorendicanhydride, and methyltetrahydrophthalic anhydride; aromaticpolycarboxylic anhydrides such as trimellitic anhydride, pyromelliticanhydride, and benzophenone-tetracarboxylic dianhydride; andpolycarboxylic anhydride derivatives thereof such as5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylicanhydride may be used. Among other polybasic acid anhydrides citedabove, tetrahydrophthalic anhydride and hexahydrophthalic anhydrideprove to be particularly desirable.

Then, as concrete examples of the compound (d) having at least twohydroxyl groups and one reactive group (such as, for example, carboxylgroup or secondary amino group) other than the hydroxyl group capable ofreacting with an epoxy group in its molecule and used for the synthesesof the resins (5) and (7) mentioned above, for example,polyhydroxy-containing monocarboxylic acids such as dimethylol propionicacid, dimethylol acetic acid, dimethylol butyric acid, dimethylolvaleric acid, and dimethylol caproic acid; and dialkanol amines such asdiethanol amine and diisopropanol amine may be cited. As theparticularly desirable compound, dimethylol propionic acid etc., forexample, may be cited.

As concrete examples of the unsaturated monoisocyanate (e) mentionedabove, for example, methacryloyl isocyanate, methacryloyl oxyethylisocyanate, and the reaction products resulting from the reaction oforganic diisocyanates (such as, for example, tolylene diisocyanate,xylylene diisocyanate, isophorone diisocyanate, and hexamethylenediisocyanate) with (meth)acrylates having one hydroxyl group in itsmolecule mentioned above at a substantially equimolar ratio may becited.

As a polymerization initiator of the component (B), a photo-radicalpolymerization initiator and/or heat radical polymerization initiatorwhich generates radicals by irradiation of an actinic energy ray or byheating may be used.

As the photo-radical polymerization initiator to be used as thepolymerization initiator (B), any known compounds which generateradicals by irradiation of an actinic energy ray may be used. Asconcrete examples thereof, acetophenones such as acetophenone,2,2-dimethoxy-2-phenyl acetophenone, 2,2-diethoxy-2-phenyl acetophenone,p-dimethylaminopropiophenone, dichloroacetophenone,trichloroacetophenone, p-tert-butyl trichloroacetophenone,1-hydroxycyclohexyl phenyl ketone,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, andN,N-dimethyl-aminoacetophenone; benzophenones such as benzophenone,methylbenzophenone, 2-chlorobenzophenone, 4,4′-dichlorobenzophenone,4,4′-bis(dimethylamino)benzophenone, 4,4′-bis(diethylamino)benzophenone,Michler's ketone, and 4-benzoyl-4′-methyl-diphenyl sulfide; benzil,benzoin, and benzoin ethers such as benzoin methyl ether, benzoin ethylether, benzoin isopropyl ether, and benzoin isobutyl ether; ketals suchas acetophenone dimethyl ketal and benzyl dimethyl ketal; thioxanthonessuch as thioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone,2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; anthraquinonessuch as 2-methyl-anthraquinone, 2-ethyl-anthraquinone,2-tert-butyl-anthraquinone, 1-chloroanthraquinone,2-amino-anthraquinone, and 2,3-diphenyl-anthraquinone; organic peroxidessuch as benzoyl peroxide and cumene peroxide; thiol compounds such asdimer of 2,4,5-triaryl imidazole, riboflavin tetrabutylate,2-mercaptobenzimidazole, 2-mercaptobenzoxazole, and2-mercaptobenzothiazole; organic halogen compounds such as2,4,6-tris-S-triazine, 2,2,2-tribromoethanol, and tribromomethyl phenylsulfone; and 2,4,6-trimethylbenzoyl diphenyl phosphine oxide may becited. These compounds may be used either singly or in the form of acombination of two or more members. Optionally, the photo-radicalpolymerization initiator may be used in combination with one member or amixture of two or more members selected from the photosensitizers suchas tertiary amines like N,N-(dimethylamino)ethylbenzoate,N,N-(dimethylamino)isoamyl benzoate, penthyl-4-dimethylaminobenzoate,triethyl amine, and triethanol amine, thioethers such as β-thiodiglycol;sensitizing dyestuff such as (keto)cumalin and thioxantene, and alkylborates of such dyestuff as cyanine, rhodamine, safranine, malachitegreen, and methylene blue.

The preferred combinations of the photo-radical polymerizationinitiators include the combinations of2-methyl-1-[4-(methylthio)-phenyl]-2-morphorino-propan-1-one (such as,for example, Irgacure 907 produced by Ciba Specialty Chemicals Ltd.)with 2-chlorothioxanthone (such as, for example, Kayacure-CTX producedby Nippon Kayaku Co., Ltd.), 2,4-diethylthioxanthone (such as, forexample, Kayacure-DETX produced by Nippon Kayaku Co., Ltd.),2-isopropylthioxanthone, or 4-benzoyl-4′-methyldiphenyl sulfide, forexample. The amount of the aforementioned photo-radical polymerizationinitiator to be used suitably falls in the range of 0.2 to 30 parts byweight, preferably 2 to 10 parts by weight, based on 100 parts by weightof the aforementioned photosensitive prepolymer (A). If the amount ofthe photo-radical polymerization initiator to be used is less than 0.2part by weight, the composition will suffer from inferior photo-curingproperties. Conversely, if the amount exceeds 30 parts by weight, thecomposition will entail the disadvantage of exhibiting inferior qualityfor cured film and poor stability during storage.

As the heat radical polymerization initiators which are usable in thepresent invention, organic peroxides such as benzoyl peroxide, acetylperoxide, methyl ethyl ketone peroxide, lauroyl peroxide, dicumylperoxide, di-t-butyl peroxide, t-butyl hydroperoxide, and cumenehydroperoxide; and azo type initiators such as2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile,2,2′-azobis-2,4-divaleronitrile, 1,1′-azobis(1-acetoxy-1-phenylethane),1′-azobis-1-cyclohexane carbonitrile, dimethyl-2,2′-azobisisobutylate,4,4′-azobis-4-cyanovalic acid, and 2-methyl-2,2′-azobispropanenitrilemay be cited. As the preferred initiator,1,1′-azobis(1-acetoxy-1-phenylethane) of the non-cyane and non-halogentype is cited. The heat radical polymerization initiator is used in therange of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight,based on 100 parts by weight of the photosensitive prepolymer (A)mentioned above.

When an organic peroxide which exhibits a lower curing rate is used asthe heat radical polymerization initiator, tertiary amines such astributylamine, triethylamine, dimethyl-p-toluidine, dimethylaniline,triethanolamine, and diethanolamine, or metallic soap such as cobaltnaphthenate, cobalt octoate, and manganous naphthenate may be used as apromotor.

As the diluent of the component (C) mentioned above, an organic solventand/or a photopolymerizable monomer may be used. As the organicsolvents, ketones such as methyl ethyl ketone and cyclohexanone;aromatic hydrocarbons such as toluene, xylene, and tetramethyl benzene;glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve,carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethylether, dipropylene glycol monomethyl ether, dipropylene glycol diethylether, and triethylene glycol monoethyl ether; acetates such as ethylacetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate,carbitol acetate, butyl carbitol acetate, propylene glycolmonomethylether acetate, and dipropylene glycol monomethyl etheracetate; alcohols such as ethanol, propanol, ethylene glycol, andpropylene glycol; aliphatic hydrocarbons such as octane and decane; andpetroleum solvents such as petroleum ether, petroleum naphtha,hydrogenated petroleum naphtha, and solvent naphtha may be cited. Theseorganic solvents may be used either singly or in the form of acombination of two or more members.

The organic solvent is used for the purpose of dissolving thephotosensitive prepolymer (A) mentioned above, diluting the composition,allowing the composition to be applied to a substrate in the from of aliquid, enabling the applied layer of the composition to form a film bythe predrying, and allowing the film to be exposed to light by thescontact exposure, or for the purpose of allowing the composition to beapplied to a supporting film and enabling the applied layer of thecomposition to form a film by the predrying to prepare a photosensitivedry film. Though the amount of the organic solvent to be used is notparticularly restricted, it is properly in the approximate range of 30to 300 parts by weight, based on 100 parts by weight of thephotosensitive prepolymer (A) mentioned above. The amount of the organicsolvent may be suitably set so as to fit the method of application to beselected.

As typical examples of the photopolymerizable monomers, 2-hydroxyethylacrylate, 2-hydroxypropyl acrylate, N-vinylpyrrolidone, acryloylmorpholine, methoxytetraethylene glycol acrylate, methoxypolyethyleneglycol acrylate, polyethylene glycol diacrylate, N,N-dimethylacrylamide, N-methylol acrylamide, N,N-dimethylaminopropyl acrylamide,N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl acrylate,melamine acrylate, diethylene glycol diacrylate, triethylene glycoldiacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate,tripropylene glycol diacrylate, polypropylene glycol diacrylate,phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, cyclohexyl acrylate,glycerin diglycidyl ether diacrylate, glycerin triglycidyl ethertriacrylate, isobornyl acrylate, cyclopentadiene mono- or di-acrylate;polyfunctional acrylates of polyhydric alcohols such as hexane diol,trimethylol propane, pentaerythritol, ditrimethylol propane,dipentaerythritol, and tris-hydroxyethyl isocyanurate and of ethyleneoxide or propylene oxide adducts thereof; methacrylates corresponding tothe acrylates enumerated above; and mono-, di-, tri-, and higherpolyesters of polybasic acids with hydroxyalkyl (meth)acrylates may becited. These monomers may be used either singly or in the form of acombination of two or more members.

The aforementioned photopolymerizable monomer is used for the purpose ofdiluting the aforementioned photosensitive prepolymer thereby renderingthe produced composition easily applicable, and impartingphotopolymerizability upon the composition. The preferred amount of themonomer to be used is in the range of 3 to 50 parts by weight, based on100 parts by weight of the photosensitive prepolymer (A) mentionedabove. If the amount of the monomer is less than 3 parts by weight, thecomposition will be at a disadvantage in failing to enhance thephoto-curing properties. Conversely, if the amount exceeds 50 parts byweight, the composition will be at a disadvantage in failing to heightendryness of the film to the tack-free touch of finger.

The photocurable and thermosetting resin composition of the presentinvention, besides the components described above, contains further anoxetane compound (D) having at least two oxetanyl groups in its moleculeas a thermosetting component. As a result, this composition can beadvantageously used for the formation of various resinous insulatinglayers, for the use as an etching resist and a marking ink, and for theformation of a solder resist on printed circuit boards.

As typical examples of the compound containing two oxetane rings in itsmolecule, bisoxetanes represented by the following general formula (5)may be cited.

In the general formula (5) mentioned above, R⁶ represents a hydrogenatom or an alkyl group of 1 to 6 carbon atoms, and R⁷ represents abivalent group selected from among linear or branched saturatedhydrocarbons of 1 to 12 carbon atoms, linear or branched unsaturatedhydrocarbons of 1 to 12 carbon atoms, aromatic hydrocarbons representedby the following formulas (A), (B), (C), (D), and (E), linear or cyclicalkylene groups containing a carbonyl group and represented by thefollowing formulas (F) and (G), and aromatic hydrocarbons containing acarbonyl group and represented by the following formulas (H) and (I).

wherein R⁸ represents a hydrogen atom, an alkyl group of 1 to 12 carbonatoms, an aryl group, or an aralkyl group, R⁹ represents —O—, —S—,—CH₂—, —NH—, —SO₂—, —CH(CH₃)—, —C(CH₃)₂—, or —C(CF₃)₂—, and R¹⁰represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms.

wherein n represents an integer of 1 to 12.

As typical examples of the compound containing three or more oxetanerings in its molecule, etherified products of an oxetane with a hydroxylgroup-containing resin such as a novolak resin, poly(p-hydroxy styrene),cardo type oxetane resin, calixarenes, or a silicone resin like acylseski oxane besides a compound represented by the following generalformula (6) may be cited. In addition thereto, a copolymer of anunsaturated monomer containing an oxetane ring and an alkyl(meth)acrylate may be cited.

In the general formula (6) mentioned above, R⁶ represents the samemeaning as mentioned above, R¹¹ represents a residue of the hydroxylgroup-containing resin of the etherified product mentioned above, abranched alkylene group of 1 to 12 carbon atoms represented by thefollowing formula (J), (K) or (L), or an aromatic hydrocarbonrepresented by the following formula (M), (N) or (P), and m representsthe number of functional groups bonded to the residue R¹¹, an integer ofthree or more, preferably an integer of 3 to 5,000.

wherein R¹² represents a hydrogen atom, an alkyl group of 1 to 6 carbonatoms, or an aryl group.

The polyfunctional oxetane compounds (D) may be used either singly or inthe form of a combination of two or more members. Among other oxetanecompounds cited above, the finely pulverized oxetane resins whichexhibit sparing solubility in a diluent to be used or a combination ofthe sparingly soluble oxetane resin and the soluble oxetane resin proveto be particularly desirable. The amount of the polyfunctional oxetanecompound (D) mentioned above to be incorporated in the composition as athermosetting component is desired to be in the range of 5 to 100 partsby weight, preferably 15 to 60 parts by weight, based on 100 parts byweight of the photosensitive prepolymer (A) mentioned above.

As a curing promotor (E), any compound may be arbitrarily selected fromamong tertiary amines, tertiary amine salts, quaternary onium salts,tertiary phosphines, imidazole derivatives, and crown ether complex(such as, for example, 18-crown-6/potassium phenoxide, potassiumbenzoether, KCl, KBr or ammonium acetate). These compounds may be usedeither singly or in the form of a combination of two or more members.Besides, a phosphonium ylide etc. may be used.

As the tertiary amine, triethylamine, tributylamine, DBU(1,8-diazabicyclo[5.4.0]undeca-7-ene), DBN(1,5-diazabicyclo[4.3.0]nona-5-ene), DABCO(1,4-diazabicyclo[2.2.2]octane), pyridine, N,N-dimethyl-4-aminopyridine, etc. may be cited.

As the tertiary amine salt, U-CAT series of Sun-Apro K.K., for example,may be cited.

Further, a quaternary onium salt obtained by the addition reaction of atertiary amine or a tertiary phosphine with a carboxylic acid or ahighly acidic phenol may be used as the reaction promotor. They may bein the form of a quaternary salt before adding to the reaction system.Alternatively, they may be individually added to the reaction system soas to form the quaternary salt in the reaction system. As the concreteexamples thereof, tributylamine acetic acid salt obtained fromtributylamine and acetic acid and triphenylphosphine acetic acid saltformed from triphenylphosphine and acetic acid may be cited.

As the quaternary onium salt, ammonium salts, phosphonium salts,arsonium salts, stibonium salts, oxonium salts, sulfonium salts,selenonium salts, stannonium salts, iodonium salts, etc. may be cited.Particularly preferable salts are quaternary ammonium salts andquaternary phosphonium salts. As concrete examples of the quaternaryammonium salts, tetra-n-butylammonium chloride (TBAC),tetra-n-butylammonium bromide (TBAB), tetra-n-butylammonium iodide(TBAI), and tetra-n-butylammonium acetate (TBAAc) may be cited. Asconcrete examples of the quaternary phosphonium salts,tetra-n-butylphosphonium chloride (TBPC), tetra-n-butylphosphoniumbromide (TBPB), tetra-n-butylphosphonium iodide (TBBI),tetraphenylphosphonium chloride (TPPC), tetraphenylphosphonium bromide(TPPB), tetraphenylphosphonium iodide (TPPI), ethyltriphenylphosphoniumbromide (ETPPB), ethyltriphenylphosphonium acetate (ETPPAc), etc. may becited.

As the tertiary phosphine, any trivalent organic phosphorus compoundscontaining an alkyl group of 1 to 12 carbon atoms or an aryl group maybe used. As the concrete examples thereof, triethylphosphine,tributylphosphine, triphenylphosphine, etc. may be cited.

As the imidazole derivatives, imidazole, 2-methylimidazole,2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole,4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole,1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, etc. may be cited. Thecompounds which are commercially available include products of ShikokuChemicals Co., Ltd., 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4 MHZ. As thecompounds which can improve the stability with time, the products ofAsahi-Ciba Co., Ltd., Novacure HX-3721, HX-3748, HX-3741, HX-3088,HX-3722, HX-3742, HX-3921HP, HX-3941HP, HX-3613, etc. may be cited.

Although any known compounds obtained by the reaction of a phosphoniumsalt and a base may be used as the phosphonium ylide, a highly stablecompound is preferable from the viewpoint of easy handling. As concreteexamples thereof, (formylmethylene)triphenylphosphine,(acetylmethylene)triphenylphosphine,(pivaloylmethylene)triphenylphosphine,(benzoylmethylene)triphenylphosphine,(p-methoxybenzoylmethylene)triphenylphosphine,(p-methylbenzoylmethylene)triphenylphosphine,(p-nitrobenzoylmethylene)triphenylphosphine,(naphthoyl)triphenylphosphine, (methoxycarbonyl)triphenylphosphine,(diacetylmethylene)triphenylphosphine, (acetylcyano)triphenylphosphine,(dicyanomethylene)triphenylphosphine, etc. may be cited.

The amount of the curing promotor (E) to be used is preferred to be inthe approximate range of 0.1 to 25 mol %, more preferably 0.5 to 20 mol%, most preferably 1 to 15 mol %, based on one mol of the oxetanylgroup. If the amount of the curing promotor to be used is less than 0.1mol % of the oxetanyl group, the reaction will not proceed at apractical reaction speed. Conversely, a large amount exceeding 25 mol %is not desirable from the economical viewpoint because a remarkablereaction promotion effect will not be obtained even when the promotor ispresent in such a large amount.

As described above, since the reactivity of the polyfunctional oxetanecompound is lower than that of the polyfunctional epoxy compound, thephotocurable and thermosetting resin composition containing thepolyfunctional oxetane compound exhibits longer shelf life (usefullife), can be formulated as a one package preparation, and allowsformation of a photosensitive dry film which can be stored at roomtemperature. However, when it takes relatively much time from thepreparation of the composition to the beginning of use thereof or to theapplication to a supporting film, since the composition containing thethermosetting component added thereto in advance is liable to gain inviscosity prior to being applied to a blank circuit board or to asupporting film, it is proper to have them mixed immediately prior touse. To be specific, it is appropriate to prepare two separatesolutions, i.e. a hardener solution comprising the aforementionedpolyfunctional oxetane compound (D) as a main component and a main agentsolution comprising the aforementioned photosensitive prepolymer (A) asa main component and the curing promotor (E) etc. added thereto and, andmix these solutions prior to use. The aforementioned photopolymerizablemonomers, fillers, coloring pigments, etc. may be mixed into a solventsolution of the polyfunctional oxetane compound (D) as the thermosettingcomponent.

In the photocurable and thermosetting resin composition of the presentinvention, an epoxy compound may be mixed as part of the thermosettingcomponent in a proportion not so large as to adversely affect theeffects of the use of the polyfunctional oxetane compound as thethermosetting component. As the epoxy compound mentioned above, anycompound my be used insofar as it has at least two epoxy groups in itsmolecule. As the examples of the epoxy compound, various well-known andpopularly adopted epoxy compounds such as, for example, glycidyl ethercompounds such as bisphenol A epoxy resin, bisphenol F epoxy resin,bisphenol S epoxy resin, brominated bisphenol A epoxy resin,hydrogenated bisphenol A epoxy resin, biphenol epoxy resin, bixylenolepoxy resin, alicyclic epoxy resin, phenol novolak epoxy resin, cresolnovolak epoxy resin, brominated phenol novolak epoxy resin, and novolakepoxy resin of bisphenol A; glycidyl ester compounds such asterephthalic diglycidyl ester, hexahydrophthalic diglycidyl ester, anddimeric diglycidyl ester; and glycidyl amine compounds such astriglycidyl isocyanurate, N,N,N′,N′-tetraglycidyl methaxylene diamine,N,N,N′,N′-tetraglycidyl bis(aminomethyl)-cyclohexane, and N,N-diglycidylaniline may be used. These epoxy compounds may be used either singly orin the form of a combination of two or more members. Although any epoxycompounds which exhibit sparing solubility or solubility in a diluent(C) to be used may be used as the epoxy compound, the finely pulverizedepoxy compound which exhibits sparing solubility in a diluent and is inthe state of solid or semi-solid at room temperature or a combination ofthis sparingly soluble epoxy compound and the soluble epoxy compoundprove to be particularly desirable from the viewpoint of developabilityetc.

Further, for the purpose of promoting the thermal curing reaction, asmall amount of a well-known epoxy curing promotor such as quaternaryammonium salts, quaternary phosphonium salts, tertiary amines,imidazoles, and dicyandiamide may be used in combination therewith.

The composition of the present invention may incorporate therein, asdesired, a well-known and widely used inorganic filler such as bariumsulfate, barium titanate, silicon dioxide power, amorphous silica, talc,magnesium carbonate, calcium carbonate, aluminum oxide, aluminumhydroxide, glass fiber, carbon fiber, and mica power for the purpose ofenhancing the characteristics of the composition such as adhesion andhardness. The amount of the inorganic filler to be used is in the rangeof 0 to 60% by weight, preferably 5 to 40% by weight of the composition.Further, the composition may incorporate therein, as desired, awell-known and widely used additive such as a coloring pigmentrepresented by phthalocyanine blue, phthalocyanine green, Iodine Green,disazo yellow, crystal violet, titanium dioxide, carbon black, andnaphthalene black; a thermopolymerization inhibitor represented byhydroquinone, hydroquinone monomethyl ether, t-butyl catechol,pyrogallol, and phenothiazine; a thickening agent represented byasbestos and finely powdered silica; an anti-foaming agent and/orleveling agent represented by silicone type, fluorine type, ormacromolecular type; and an adhesiveness-imparting agent represented byimidazole type, thiazole type, triazole type, and silane coupling agent.

In the manufacture of a photosensitive dry film of the presentinvention, the photocurable and thermosetting resin composition of thepresent invention as mentioned above is adjusted, when necessary, to alevel of viscosity suitable for the coating method, applied to asuitable supporting film such as, for example, a flexible base film, andthen dried at a temperature in the range of about 60 to 100° C., forexample, thereby to evaporate the organic solvent from the compositionand give rise to a photosensitive dry film which has a tack-freephotocurable and thermosetting dry film layer. It is preferred topreserve the photocurable and thermosetting dry film layer until usethereof in such a state that the dry film layer formed on the supportingfilm is protected by a protective film laminated thereon.

As the supporting film, various synthetic resin films made of, forexample, polyethylene terephthalate (PET), polyethylene (PE),polypropylene, polycarbonate, polyether sulfone, or polyvinyl chloridemay be used. The proper thickness of this supporting film is in therange of 15 to 125 μm.

For the formation of a coating film, various coating methods using anapplicator, a bar coater, a roll coater, a die coater, a curtain flowcoater, etc. or the screen printing method and the like may be adopted.The proper thickness of the coating film is in the range of 10 to 150 μmas the thickness after drying.

The protective film to be laminated on the dry film layer is used forstably protecting the dry film at the time of not putting to use andremoved at the time of use. Therefore, it should have such properrelease characteristics that it is not peeled off at the time of notputting to use, but it can be easily separated from the dry film layerat the time of use. As the protective film which fulfills suchrequirements, a PET film, a polypropylene film, a PE film, etc. may beused. Further, the above-mentioned film further coated with silicone orbaked may be used. This protective film is preferred to have a thicknessin the range of about 15 to 100 μm.

Moreover, for the purpose of preventing the photocurable andthermosetting resin composition from suffering the sensitivity reductionowing to oxygen and adhesion of the photo-mask for pattern formation tobe tightly laminated thereon at the time of exposure, it is possible tofurther form a layer of a water-soluble resin composition on the dryfilm layer. In the case of such a photosensitive dry film, it ispreserved by laminating the protective film on the layer of thewater-soluble resin composition. The layer of the water-soluble resincomposition is formed by applying an aqueous 5–20 wt. % solution ofpolyvinyl alcohol or partially saponified polyvinyl acetate to the dryfilm layer in such a proportion that the thickness may become 1–10 μm asthe dry film thickness and drying it.

Incidentally, ethylene glycol, propylene glycol, polyethylene glycol,etc. may also be added to the solution of the water-soluble resincomposition. In the preparation of this solution, when taking theviscosity and anti-foaming properties thereof into consideration, asolvent such as, for example, methanol, ethylene glycol monomethyl etheracetate, and acetone or a commercially available water-solubleanti-foaming agent or the like may also be added thereto.

Now, a method of forming a pattern by the use of the photocurable andthermosetting resin composition of the present invention is describedhereinbelow. First, the composition is adjusted, when necessary, to alevel of viscosity suitable for the coating method, applied by a screenprinting method, a curtain coating method, a dip coating method, a spraycoating method, a roll coating method, a spin coating method, or thelike to a printed circuit board having a circuit already formed thereon,for example, and then predried at a temperature in the approximate rangeof 60 to 100° C., for example, thereby to evaporate the organic solventfrom the composition and give rise to a tack-free coating film. Then,the composition coated on the printed circuit board is selectivelyexposed to an actinic ray through a photomask having a prescribedpattern by the contact method or non-contact method and the compositionin the unexposed areas of the coating film is developed with a diluteaqueous alkaline solution (such as, for example, an aqueous solution ofabout 0.5 to 5% sodium carbonate) to obtain a resist pattern.Thereafter, the photo-cured coating film is further thermally cured bysubjecting to the heat treatment at a temperature in the approximaterange of 140 to 200° C., for example. By this thermal treatment, inaddition to the curing reaction of the aforementiond thermosettingcomponents, the polymerization of the photocurable resin components ispromoted and the copolymerization of this component with thethermosetting component are also facilitated so that the consequentlyproduced resist film acquires improvements in various properties such asresistance to heat, resistance to adhesion of solder, resistance tosolvents, resistance to acids, adhesiveness, resistance to electrolessgold plating, electric properties, printability, and hardness.

When the composition is also used as a material for the interlaminarinsulating layer in a build-up multi-layer printed circuit board, apattern may be formed in the same manner as mentioned above.

Next, a pattern forming method by the use of the photosensitive dry filmof the present invention is explained.

First, when the photosensitive dry film has a protective film, theprotective film is separated therefrom. The photosensitive dry film istightly superposed on a substrate on which a pattern is formed in such amanner that a dry film layer is brought into contact with the substrate,and a supporting film is separated, thereby transferring the dry filmlayer consisting of the photocurable and thermosetting resin compositionto the substrate. As the transferring method, a hot press bonding methodwhich comprises previously heating the substrate to be processed isdesirable. A vacuum bonding method which achieves press boding undervacuum may also be adopted. Although the substrate to be processed canbe arbitrarily chosen according to the usage of the photosensitive dryfilm aimed at. When it is used as a solder resist for a printed circuitboard, for example, it is transferred to the printed circuit boardhaving circuits previously formed thereon. When it is used as aninterlaminar insulating layer for a build-up multi-layer printed circuitboard, it is transferred to an inner board.

The dry film layer transferred is exposed to light through a patternmask and subsequently developed to remove the unexposed areas, therebyforming a pattern.

Thereafter, in the case of the formation of a solder resist, forexample, the dry film layer is selectively exposed to an actinic raythrough a photomask having a prescribed pattern by a contact exposuremethod or non-contact exposure method and the unexposed areas of thefilm is removed by development with a dilute aqueous alkaline solution(such as, for example, an aqueous solution of about 0.5 to 5% sodiumcarbonate) to form a resist pattern. Then, the film is further thermallycured by subjecting to the heat treatment at a temperature in the rangeof about 140 to 200° C., for example. By this thermal treatment, inaddition to the curing reaction of the aforementiond thermosettingcomponents, the polymerization of the photocurable resin components ispromoted and the cross-linking reaction of this component with thethermosetting component are also facilitated so that the consequentlyproduced resist film acquires improvements in various properties such asresistance to heat, resistance to adhesion of solder, resistance tosolvents, resistance to acids, adhesiveness, resistance to electrolessgold plating, electric properties, printability, and hardness.

As an aqueous alkaline solution to be used in the process of developmentmentioned above, aqueous alkaline solutions of potassium hydroxide,sodium hydroxide, sodium carbonate, potassium carbonate, sodiumphosphate, sodium silicate, ammonia, tetramethylammonium hydroxide,organic amines, etc. can be used.

The light sources which are properly used for the purpose ofphoto-curing the composition include a low-pressure mercury lamp, amedium-pressure mercury lamp, a high-pressure mercury lamp, anultra-high-pressure mercury lamp, a xenon lamp, and a metal halide lamp,for example. The laser beams and electron beams may also be utilized asthe actinic ray for exposure of the film.

Now, the present invention will be described more specifically belowwith reference to working examples and comparative examples. It shouldbe noted, however, that the following Examples are intended to be merelyillustrative of and in any sense restrictive of the present invention.Wherever the term “parts” is used hereinbelow, it shall refer to “partsby weight” unless otherwise specified.

Preparation of Photosensitive Prepolymers

SYNTHESIS EXAMPLE 1

Into a four-necked flask equipped with a stirrer and a reflux condenser,220 parts of cresol novolak type epoxy resin (manufactured by DainipponInk and Chemicals Inc., registered trademark “EPICLON” N-695, epoxyequivalent: 220) was charged and then 214 parts of carbitol acetate wasadded thereto and they were molten by heating. Then, 0.1 part ofhydroquinone as a polymerization inhibitor and 2.0 parts ofdimethylbenzylamine as a reaction catalyst were added thereto. Theresultant mixture was heated to 95–105° C., 72 parts of acrylic acid wasgradually added dropwise thereto, and they were left reacting for 16hours. The resultant reaction product was cooled to 80–90° C., 106 partsof tetrahydrophthalic anhydride was added thereto, and the mixture wasleft reacting for 8 hours and cooled, and then the reaction product wasextracted therefrom.

The photosensitive resin having ethylenically unsaturated bonds togetherwith carboxyl groups obtained as described above had a nonvolatilecontent of 65%, an acid value of a solid content of 100 mg KOH/g, and aweight-average molecular weight, Mw, of about 3,500. Hereinafter, thisresin solution will be referred to as varnish “a”.

Incidentally, the weight-average molecular weight of the obtained resinwas determined by gel permeation chromatography connected to pumpsmanufactured by Shimadzu Seisakusho Ltd., LC-804, KF-803, and KF-802.

SYNTHESIS EXAMPLE 2

Into a flask equipped with a thermometer, a stirrer, a dropping funnel,and a reflux condenser, methyl methacrylate and glycidyl methacrylatewere charged in a molar ratio of 4:6 and carbitol acetate as a solventand azobisisobutyronitrile as a polymerization initiator were addedthereto and they were together stirred under an atmosphere of nitrogengas at 80° C. for 4 hours to obtain a resin solution. The resultantresin solution was cooled and, in the presence of methyl hydroquinoneused as a polymerization inhibitor and tetrabutyl phosphonium bromideused as a catalyst, subjected to addition reaction of acrylic acid at aratio of 100% of the epoxy groups of the resin mentioned above under theconditions of 95–105° C. and 16 hours. The reaction product was cooledto 80–90° C., subjected to the reaction with tetrahydrophthalicanhydride for 8 hours, cooled, and then extracted therefrom.

The photosensitive resin having ethylenically unsaturated bonds togetherwith carboxyl groups obtained as described above had a nonvolatilecontent of 65%, an acid value of a solid content of 100 mg KOH/g, and Mwof about 15,000. Hereinafter, this resin solution will be referred to asvarnish “b”.

SYNTHESIS EXAMPLE 3

In 463 parts of dimethyl sulfoxide, 350 parts of a bisphenol A typeepoxy resin (EPIKOTE 1004 produced by Japan Epoxy Resin K.K., epoxyequivalent: 917) and 925 parts of epichlorohydrin were dissolved. Theresultant solution was kept stirred at 70° C. and 61 parts of 99% NaOHwas added meanwhile thereto over a period of 100 minutes. After theaddition, the reaction was continued at 70° C. for three hours. Afterthe reaction was completed, the reaction solution was washed with 250parts of water. After the separation of oil from the mixture, the oillayer was distilled under a reduced pressure to recover the greater partof dimethyl sulfoxide and the excess of unreacted epichlorohydrin. Thereaction product containing a residual by-produced salt and dimethylsulfoxide was dissolved in 750 parts of methyl isobutyl ketone. Theresultant solution and 10 parts of 30% NaOH added thereto were leftreacting at 70° C. for two hours. After the reaction was completed, thereaction mixture was washed twice with 200 parts of water to separateoil. Thereafter, the oil layer was distilled to recover methyl isobutylketone and obtain an epoxy resin having an epoxy equivalent of 318. Theepoxy resin thus obtained was found by a calculation based on the epoxyequivalent to have resulted from the epoxidization of about 4.8 of 5.3alcoholic hydroxyl groups in the bisphenol A type epoxy resin as thestarting material mentioned above.

Into a flask, 318 parts of this epoxy resin and 351 parts of carbitolacetate were charged. The mixture was heated and stirred to 90° C. untildissolution. To this solution, 0.4 part of methyl hydroquinone, 72 partsof acrylic acid, and 4 parts of triphenyl phosphine were added and theywere heated to 90 to 95° C. and left reacting for 36 hours. Thus, areaction product having an acid value of 2.2 mg KOH/g was obtained.After this reaction solution was cooled to room temperature, 137 partsof tetrahydrophthalic anhydride was added thereto, and they were heatedto 85° C. and left reacting.

The photosensitive resin having ethylenically unsaturated bonds togetherwith carboxyl groups obtained as described above had a nonvolatilecontent of 60%, an acid value of a solid content of 96 mg KOH/g, and Mwof about 8,800. Hereinafter, this resin solution will be referred to asvarnish “c”.

The raw materials used in the following working examples and comparativeexamples are shown in Table 1.

TABLE 1 Components Chemical name or product name Main PhotosensitiveVarnish “a” obtained in Synthesis agent prepolymer Example 1 Varnish “b”obtained in Synthesis Example 2 Varnish “c” obtained in SynthesisExample 3 Filler Silica Photo-radical2-Methyl-1-[4-(methylthio)phenyl]-2- polymerizationmorphorino-propan-1-one initiator Coloring pigment Phthalocyanine greenCuring a Tetraphenyl phosphonium bromide promotor b Imidazol cDicyandiamide Diluent Dipropylene glycol monomethyl ether Silicone-basedKS-66 (manufactured by Shinetsu anti-foaming agent Chemical IndustriesCo., Ltd.) Additive Organobentonite Hardener PhotopolymerizableDipentaerythritol hexaacrylate monomer Epoxy resin TEPIC (manufacturedby Nissan Chemical Industries Ltd.) Oxetane resin a Terephthalatebisoxetane b Xylylene bisoxetane Diluent Dipropylene glycol monomethylether

EXAMPLES 1–5 AND COMPARATIVE EXAMPLE 1

The main agent solution of each of the examples shown in Table 2 wasprepared by compounding relevant components at proportions showncorrespondingly in the same table and kneading them with a three-rollmill. The hardener solution of the same example was prepared similarlyby compounding relevant components at proportions shown in Table 2 andkneading them with the three-roll mill. A two-package type photocurableand thermosetting resin composition thus obtained was prepared for useby mixing the main agent solution and the hardener solution.

TABLE 2 Comp. Exam- Components Examples ple and amounts (parts) 1 2 3 45 1 Main Varnish a 100 — — 100 100 100 agent (solid b — 100 — — — —content) c — — 100 — — — Filler 30 30 30 30 30 30 Photo-radical 10 10 1010 10 10 polymerization initiator Coloring pigment 1 1 1 1 1 1 Curing a— — — — 3.5 — promotor b 3.5 3.5 3.5 3.5 — 3.5 c — — — — — 0.5 Diluent10 10 10 10 10 10 Silicone-based 1 1 1 1 1 1 anti-foaming agent Additive5 5 5 5 5 5 Hard- Photopolymerizable 20 20 20 20 20 20 ener monomerEpoxy resin — — — — — 30 Oxetane resin a 30 30 30 — 30 — b — — — 30 — —Diluent 5 5 5 5 5 5Evaluation of Quality:(1) Storage Stability

The two-package type photocurable and thermosetting resin compositionsprepared as described above were left standing at 50° C. for one weekafter mixing and their state at the end of the standing were examined toevaluate the storage stability. As a result, the resin composition ofComparative Example 1 has solidified. On the contrary, the resincompositions of Examples 1 to 5 have maintained their liquid statewithout causing gelation. To be specific, this means that the resincomposition of the present invention excels in storage stability and canbe formulated as a one package preparation.

(2) Developability

The photocurable and thermosetting resin compositions obtained inExamples 1–5 and Comparative Example 1 were each applied by the screenprinting method onto the entire surface of a copper-clad substrate andthen dried by heating at 80° C. for 30 minutes. Each substrate wasentirely exposed to light by using a high pressure mercury lamp througha negative film with a prescribed exposure dose and then developed withan aqueous 1 wt % Na₂CO₃ solution used as a developing solution underthe condition of a spraying pressure of 2 kg/cm² for one minute to forma resist pattern thereon. The developability was visually examinedthrough a microscope and rated on the following criterion.

⊚: Complete development even in very small portions

∘: Presence of thin undeveloped portions in the substrate surface

Δ: Remarkable presence of undeveloped portions

X: Almost no development

(3) Adhesiveness:

The photocurable and thermosetting resin compositions obtained inExamples 1–5 and Comparative Example 1 were each applied by the screenprinting method onto the entire surface of a printed circuit boardhaving a prescribed pattern formed in advance thereon to form a coatingfilm of about 20 μm thickness. Then, a resin pattern was formed underthe same conditions as in the test for developability in item (2)mentioned above The resultant substrate was thermally cured at 150° C.(in the case of Comparative Example) or 180° C. (in the cases ofExamples 1 to 5) for one hour to prepare a test substrate. This testsubstrate was incised like cross-cut in the shape of squares in a goboard and then subjected to a peel test with a cellophane adhesive tapein accordance with the method specified in JIS D-0202 to determine thedegree of separation of the resist layer based on the followingcriterion.

⊚: 100/100 and absolutely no peeling of the resist layer

∘: 100/100, but slight peeling in cross-cut portions

Δ: 50/100–90/100

X: 0/100–50/100

(4) Resistance to Cracking

Test substrates were prepared under the same conditions as in the testfor adhesiveness in item (3) mentioned above by using the photocurableand thermosetting resin compositions obtained in Examples 1–5 andComparative Example 1. These test substrates were subjected to the heatcycle test under the conditions of 1,000 cycles between 125° C.×30minutes and −55° C.×30 minutes to investigate the occurrence of cracks.

(5) Resistance to Soldering Heat

Test substrates were prepared under the same conditions as in the testfor adhesiveness in item (3) mentioned above by using the photocurableand thermosetting resin compositions obtained in Examples 1–5 andComparative Example 1. Each of the test substrates was coated with arosin type flux, immersed for 30 seconds in a solder bath set in advanceat 260° C., then rinsed with isopropyl alcohol to remove the fluxtherefrom, and visually examined to find the extents of swelling,separation, and discoloration consequently produced in the resist layeron the test substrate.

⊚: Perfect absence of any discernible change was found.

∘: Slight change was found.

Δ: Swelling or separation of a coating film was not more than 20%.

X: Swelling or separation of a coating film was not less than 20%.

The results of the above tests are collectively shown in Table 3.

TABLE 3 Comp. Examples Example Properties 1 2 3 4 5 1 Developability ⊚ ⊚◯ ⊚ ⊚ ⊚ Adhesiveness ⊚ ◯ ⊚ ⊚ ◯ ⊚ Resistance to cracking N N N N N YResistance to soldering ⊚ ◯ ⊚ ⊚ ◯ ⊚ heat Remarks N: Absence of cracks Y:Presence of cracks The thermal curing was carried out at a most suitablecuring temperature for epoxy resin or oxetane resin (epoxy resin: 150°C., oxetane resin: 180° C.).

As being clear from the results shown in Table 3, the photocurable andthermosetting resin compositions of the present invention obtained inExamples 1 to 5 excelled in storage stability as compared with theconventional composition and cured films excelling in resistance tocracking were obtained without causing deterioration of the propertiesof the conventional cured film. Incidentally, the insulation resistancemeasured was the same results as that obtained by the conventional curedfilm.

Preparation of Photosensitive Dry Film

The following components including the photosensitive prepolymerobtained in each of Synthesis Examples 1 to 3 (varnish a, b, and c) werekneaded with a three-roll mill to prepare the photocurable andthermosetting resin composition so as to have the formulation shown inthe following Examples 6 to 8 and Comparative Example 2. Then, theresultant composition was applied to a supporting film (PET film)thereby forming a coating film so as to give a dry film thickness of 40μm and then dried at 80° C. for 20 minutes. Thereafter, a polyethylene(PE) film of 20 μm was laminated thereon as a protective film to preparea photosensitive dry film.

EXAMPLE 6

Photosensitive prepolymer: varnish “a” 100 parts Photo-radicalpolymerization initiator:  10 parts Irgacure 907 (produced by CibaSpecialty Chemicals Ltd.) Coloring pigment: phthalocyanin green  1 partFiller: barium sulfate  30 parts Additive:  5 parts Photopolymerizablemonomer: dipentaerythritol  20 parts hexaacrylate Oxetane compound:xylylene bisoxetane  30 parts (produced by Toa Gosei K.K.) Curingpromotor: tetraphenyl phosphonium  2 parts bromide Diluent: dipropyleneglycol monomethyl ether  5 parts Total 203 parts

EXAMPLES 7 AND 8

The composition has the same components as those in Example 6 exceptthat the photosensitive prepolymer is changed to varnish “b” and varnish“c”, respectively.

COMPARATIVE EXAMPLE 2

Photosensitive prepolymer: varnish “a” 100 parts Photo-radicalpolymerization initiator:  10 parts Irgacure 907 (produced by CibaSpecialty Chemicals Ltd.) Coloring pigment: phthalocyanin green  1 partFiller: barium sulfate  30 parts Additive:  5 parts Photopolymerizablemonomer: dipentaerythritol  20 parts hexaacrylate Epoxy compound: TEPIC(produced by  30 parts Nissan Chemical Industries, Ltd.) Curingpromotor: dicyandiamide  2 parts Diluent: dipropylene glycol monomethylether  5 parts Total 203 partsTransfer to a Substrate:

The dry film layer of the photosensitive dry film was transferred byseparating the protective film from the photosensitive dry film, hotpress bonding the photosensitive surface thereof (dry film layer side)onto a substrate by the use of a laminator, and separating thesupporting film from the substrate.

Formation of Pattern:

The above-mentioned dry film layer transferred onto the substrate, witha negative mask of a prescribed pattern superposed thereon, was exposedto light with the exposure dose of 500 mJ/cm², then developed with anaqueous 1 wt. % sodium carbonate solution by spraying for 90 seconds toremove the unexposed areas, and thermally cured at 180° C. for 60minutes in the case of Examples 6–8 and at 150° C. for 60 minutes in thecase of Comparative Example 2, respectively, to form a pattern.

Evaluation of Quality:

(5a) Resistance to Soldering Heat

The dry film layer of each of the photosensitive dry films prepared byusing the compositions of Examples 6 to 8 and Comparative Example 2 wastransferred onto the substrate by the transferring method mentionedabove and thermally cured at 180° C. for 60 minutes in the case ofExamples 6–8 and at 150° C. for 60 minutes in the case of ComparativeExample 2, respectively, to prepare a test substrate.

This test substrate was visually examined to find the extents ofswelling, separation, and discoloration consequently produced in thetransferred layer on the test substrate in the same manner as in thetest for resistance to soldering heat in item (5) mentioned above. Therating criterion is the same as that in the resistance to soldering heatin item (5) mentioned above.

(1a) Storage Stability

The dry film layers of the photosensitive dry films prepared by usingthe compositions of Examples 6 to 8 and Comparative Example 2 weretransferred onto the substrates by the transferring method mentionedabove to prepare test substrates. These test substrates were kept in athermo-hygrostat at −20° C., 0° C., and 20° C., respectively. Each testsubstrate was taken from the thermo-hygrostat after 7 days, exposed tolight and developed according to the predetermined manner to test fordevelopability, and confirmed the storage stability through a microscopeon the following criterion.

⊚: Complete development even in very small portions

∘: Presence of thin undeveloped portions in the substrate surface

Δ: Remarkable presence of undeveloped portions

X: Almost no development

(3a) Adhesiveness

Test substrates were prepared under the same conditions as in the testfor resistance to soldering heat in item (5a) mentioned above andevaluated according to the same testing method and criterion as in thetest for adhesiveness in item (3) mentioned above.

The results of the above tests are collectively shown in Table 4.

TABLE 4 Comparative Examples Example Properties 6 7 8 2 Developability ⊚⊚ ⊚ ⊚ Adhesiveness ⊚ ⊚ ⊚ ⊚ Storage stability −20° C. ⊚ ⊚ ⊚ ⊚    0° C. ⊚⊚ ⊚ ◯   25° C. ⊚ ⊚ ⊚ X

As being clear from the results shown in Table 4, the photosensitive dryfilms prepared by using the photocurable and thermosetting resincompositions of the present invention remarkably excelled in storagestability at room temperature as compared with that prepared by usingthe conventional composition.

As described above, the photocurable and thermosetting resin compositionof the present invention enjoys longer shelf life (useful life), can beformulated as a one package preparation, excels in formation of finepatterns, storage stability, and developability, and is capable ofproducing a cured product excelling in various properties such asresistance to cracking (toughness), fastness of adhesion, and hardness.Accordingly, it is useful as coating materials, printing ink, adhesives,resist materials, and the like, particularly as solder resists forprinted circuit boards. Further, since the photosensitive dry film ofthe present invention prepared by using such a photocurable andthermosetting resin composition excels in storage stability at roomtemperature and has various advantages owing to the excellent propertiesas mentioned above, it is useful as various resist materials andelectrical insulating materials, particularly as solder resists forprinted circuit boards, interlaminar insulating materials for build-upmulti-layer printed circuit boards, and the like.

While certain specific embodiments and working examples have beendisclosed herein, the invention may be embodied in other specific formswithout departing from the spirit or essential characteristics thereof.The described embodiments and examples are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims rather than by theforegoing description and all changes which come within the meaning andrange of equivalency of the claims are, therefore, intended to beembraced therein.

1. A photocurable and thermosetting resin composition, characterized by comprising (A) a photosensitive prepolymer having a carboxyl group in combination with at least two ethylenically unsaturated double bonds in its molecule, (B) a photo-radical polymerization initiator, (C) a diluent, (D) an oxetane compound having at least two oxetanyl groups in its molecule, and (E) a curing promotor, wherein said photosensitive prepolymer (A) is at least one prepolymer selected from the group consisting of: (1) a prepolymer obtained by the esterification of an epoxy group of a polyfunctional epoxy compound (a) having at least two epoxy groups in its molecule with a carboxyl group of an unsaturated monocarboxylic acid (b) and the subsequent reaction of a saturated or unsaturated polybasic acid anhydride (c) with a resultant hydroxyl group, (2) a prepolymer obtained by the reaction of (meth)acrylic acid with a copolymer composed of an alkyl (meth)acrylate and a glycidyl (meth)acrylate and the subsequent reaction of a saturated or unsaturated polybasic acid anhydride (c) with a resultant reaction product, (3) a prepolymer obtained by the reaction of (meth)acrylic acid with a copolymer composed of a hydroxyalkyl (meth)acrylate, an alkyl (meth)acrylate, and a glycidyl (meth)acrylate and the subsequent reaction of a saturated or unsaturated polybasic acid anhydride (c) with a resultant product, (4) a prepolymer obtained by the partial reaction of a glycidyl (meth)acrylate with a copolymer composed of an alkyl (meth)acrylate and (meth)acrylic acid, (5) a prepolymer obtained by causing a saturated or unsaturated polybasic acid anhydride (c) to react with a reaction product (I) of a polyfunctional epoxy compound (a) having at least two epoxy groups in its molecule, an unsaturated monocarboxylic acid (b), and a compound (d) having at least two hydroxyl groups and one other reactive group other than a hydroxyl group capable of reacting with an epoxy group in its molecule, (6) a prepolymer obtained by causing a hydroxyalkyl (meth)acrylate to react with a copolymer of an unsaturated polybasic acid anhydride with an aromatic hydrocarbon having a vinyl group, and (7) a prepolymer obtained by reacting said reaction product (I) with a saturated or unsaturated polybasic acid anhydride (c) and an unsaturated group-containing monoisocyanate (e).
 2. The composition according to claim 1, wherein said diluent (C) is an organic solvent and/or a photopolymerizable monomer.
 3. The composition according to claim 1, wherein said oxetane compound (D) is a bisoxetane compound represented by the following general formula (5):

wherein, R⁶ represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, and R⁷ represents a bivalent group selected from among linear or branched saturated hydrocarbons of 1 to 12 carbon atoms, linear or branched unsaturated hydrocarbons of 1 to 12 carbon atoms, aromatic hydrocarbons represented by the following formulas (A), (B), (C), (D), and (E):

wherein R⁸ represents a hydrogen atom, an alkyl group of 1 to 12 carbon atoms, an aryl group, or an aralkyl group, R⁹ represents —O—, —S—, —CH₂—, —NH—, —SO₂—, —CH(CH₃)—, —C(CH₃)₂—, or —C(CF₃)₂—, and R¹⁰ represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, linear or cyclic alkylene groups containing a carbonyl group and represented by the following formulas (F) and (G):

wherein n represents an integer of 1 to 12, and aromatic hydrocarbons containing a carbonyl group and represented by the following formulas (H) and (I):


4. The composition according to claim 1, wherein said oxetane compound (D) is a polyfunctional oxetane compound represented by the following general formula (6):

wherein, m represents the number of functional groups bonded to the residue R¹¹, an integer of three or more, R⁶ represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, R¹¹ represents a residue of the hydroxyl group-containing resin, a branched alkylene group of 1 to 12 carbon atoms represented by the following formula (J), (K) or (L):

or an aromatic hydrocarbon represented by the following formula (M), (N) or (P):

wherein R¹² represents a hydrogen atom, an alkyl group of 1 to 6 carbon atoms, or an aryl group.
 5. The composition according to claim 1, which comprises the photo-radical polymerization initiator (B) in an amount of 0.2 to 30 parts by weight, either one of an organic solvent and a photopolymerizable monomer as the diluent (C), wherein the organic solvent being in an amount of 30 to 300 parts by weight and the photopolymerizable monomer being in an amount of 3 to 50 parts by weight, the oxetane compound (D) in an amount of 5 to 100 parts by weight, respectively based on 100 parts by weight of said photosensitive prepolymer (A), and the curing promotor (E) in a proportion of 0.1 to 25 mol% per one mol of an oxetanyl group of the oxetane compound (D).
 6. A printed circuit board having a solder resist formed thereon by the use of said photocurable and thermosetting resin composition according to claim
 1. 7. A multi-layer printed circuit board having an insulating layer formed between conductor circuit layers by the use of said photocurable and thermosetting resin composition according to claim
 1. 8. A printed circuit board having a solder resist formed thereon by the use of a photosensitive dry film, said photosensitive dry film comprising a supporting film and at least a dry film layer formed thereon from said photocurable and thermosetting resin composition set forth in claim
 1. 9. A multi-layer printed circuit board having an insulating layer formed between conductor circuit layers by the use of said a photosensitive dry film, said photosensitive dry film comprising a supporting film and at least a dry film layer formed thereon from said photocurable and thermosetting resin in composition set forth in claim
 1. 